Limit feeding nonlactating, nonpregnant beef cows with bunkered wet distillers grains plus solubles or distillers solubles1

The Professional Animal Scientist 27 (2011):456–460

©2011 American Registry of Professional Animal Scientists

L inonpregnant mit feeding nonlactating, beef cows with

bunkered wet distillers grains plus solubles or distillers solubles1 J. M. Warner, L. M. Kovarik, M. K. Luebbe, G. E. Erickson, PAS, and R. J. Rasby2 Department of Animal Science, University of Nebraska–Lincoln 68583

ABSTRACT Nonlactating, nonpregnant beef cows (593 ± 10.0 kg) were used in a completely randomized design to evaluate the performance of limit-fed diets containing bunkered wet distillers grains plus solubles (WDGS; n = 24) or bunkered condensed corn distillers solubles (DS; n = 22) compared with a control diet offered ad libitum (CON; n = 24). Cows were stratified by age and BW and randomly assigned to pens (3 pens/treatment, 7 or 8 cows per pen). The WDGS and DS were mixed and stored with 30% and 59% ground cornstalks (DM basis), respectively, for 30 d before feeding. Diets were fed for 76 d and formulated to maintain BW. Both WDGS and DS diets contained 41% by-product and 59% cornstalks at time of feeding, with DMI limited to 7.7 kg/d. The CON diet consisted of 43% bromegrass hay, 34% cornstalks, and 23% alfalfa haylage and was fed ad libitum (DMI = 10.4 kg/d). This study is a contribution of the University of Nebraska Agricultural Research Division, supported in part by funds provided through the Hatch Act. 2 Corresponding author: [email protected] 1

The WDGS diet was 4.1% fat and 0.24% sulfur. The DS diet was 5.5% fat and 0.37% sulfur on a DM basis. Initial BW and BCS among treatments were similar. Final BW was greater (P < 0.05) for cows fed WDGS (625.5 kg) than for cows fed the DS (611.8 kg) and CON treatments (610.9 kg). Gain tended (P = 0.09) to be greater for the WDGS group (0.37 kg/d) compared with the CON group (0.20 kg/d). Limit feeding diets of either WDGS or DS stored in a bunker with ground cornstalks to nonlactating beef cows results in similar performance to that of full-fed control cows. Key words: beef cow, by-product, limit feeding

INTRODUCTION Ad libitum intake of forages is a commonly used system for feeding mature beef cows (Schoonmaker et al., 2003). However, hay typically costs 50 to 100% more than corn per unit of energy (Loerch, 1996). It may be economically beneficial to use a limit-fed, high-energy diet to meet the requirements of mature cows. Restricted feeding of concentrates has

previously been used in finishing diets without reduced performance (Loerch, 1990). Loerch (1996) reported limit feeding a corn-based diet as an alternative to hay had no negative effects on cow performance, conception rate, or calf weaning weight. The recent expansion of the ethanol industry has increased the availability of by-products. Distillers grains are an excellent source of highly digestible fiber, and protein, and can be effectively used in combination with high-forage diets as an energy source (Klopfenstein et al., 2008). Data from a study by Klopfenstein et al. (2008) suggested that adding wet distillers grains plus solubles to finishing diets supplies NDF, reduces starch, and adds protein and moisture to the diet. Loy et al. (2008) determined cattle fed dried distillers grains plus solubles (DDGS) in high-forage growing diets had greater ADG and G:F compared with cattle fed a diet based on dryrolled corn. Furthermore, researchers from the same study used the NRC (1996) model to estimate the energy value of DDGS in high-forage diets and determined the TDN content of DDGS was 27% greater than that of

Limit feeding beef cows ethanol by-products

dry-rolled corn. Results from both Shike et al. (2009) and Radunz et al. (2010) indicated that both DDGS and corn-gluten feed can be successfully incorporated into limit-fed diets for beef cows. However, the effects of limit feeding beef cows either wet distillers grains plus solubles or condensed corn distillers solubles bunkered with a forage have not been previously investigated. Likewise, distillers byproducts may be purchased cheaper in the summer, which makes storage in bunkers advantageous (Waterbury and Mark, 2008). Therefore, the objective of this study was to evaluate the performance of nonlactating, nonpregnant beef cows limit fed bunkered ethanol by-products mixed with low-quality forages compared with the performance of cows offered an ad libitum control diet.

MATERIALS AND METHODS All experimental facilities and procedures described were approved by the University of Nebraska–Lincoln Institutional Animal Care and Use Committee. Nonlactating, nonpregnant beef cows (593 ± 10.0 kg) were used in a 76-d feeding experiment conducted at the University of Nebraska–Lincoln Agricultural Research

and Development Center near Mead, Nebraska. Cows were stratified by age and BW and randomly assigned to 1 of 3 treatment groups (3 pens/treatment, 7 or 8 cows per pen). Pens were assigned randomly to treatments in a completely randomized design. Treatments included bunkered wet distillers grains plus solubles mixed with cornstalks (WDGS; n = 24), bunkered condensed corn distillers solubles mixed with cornstalks (DS; n = 22), and a control diet (CON; n = 24). Treatment diets were formulated to maintain cow BW. Diets are shown in Table 1. Cows assigned to the WDGS and DS treatments were limit fed at 7.7 kg of DM per cow daily or 1.3% of BW a diet consisting of a 41:59 ratio of by-product to cornstalks (DM basis). The CON diet consisted of 43% smooth bromegrass (Bromus inermis) hay, 34% cornstalks, and 23% alfalfa (Medicago sativa) haylage (DM basis) to provide ad libitum intake. To prepare the material to be bunkered, cornstalks were ground through a 17.8-cm screen. Distillers solubles or wet distillers grains plus solubles and cornstalks were weighed into a RotoMix (Roto-Mix, Dodge City, KS) feed truck, mixed for 5 min at 1,500 rpm, and packed into a concrete bunker using a skid steer loader. The tar-

Table 1. Diet and nutrient composition of diets of wet distillers grains plus solubles (WDGS) or distillers solubles (DS) stored with cornstalks before feeding and a full-fed forage control (CON) diet (DM basis) Item WDGS, % DS, % Cornstalks, % Bromegrass hay, % Alfalfa haylage, % Diet nutrient composition, %  DM  CP  TDN  NDF

WDGS1,2,3

DS1,2,3

CON3,4

41.0 — 59.0 — —

— 41.0 59.0 — —

— — 34.0 43.0 23.0

43.9 16.0 78.4 54.8

43.9 13.6 78.4 40.9

68.1 9.3 55.8 64.3

Cows limit fed at 7.7 kg/d (DM basis). Limestone added to reach a 1.5:1 minimum ratio of Ca:P. 3 Trace mineralized salt blocks provided free choice. 4 Cows fed ad libitum at 10.4 kg/d (DM basis). 1 2

457 geted by-product to cornstalks (DM basis) ratio for storage in the bunker was 65:35. However, distillers solubles material would not adequately pack at this ratio. Consequently, cornstalks were added until the material would pack for successful storage. The resulting ratio was 41:59 distillers solubles to cornstalks (DM basis). The wet distillers grains plus solubles mix was also adjusted to a storable ratio of 70:30 wet distillers grains plus solubles to cornstalks (DM basis). Wet distillers grains plus solubles and distillers solubles bunkered material was covered with plastic and stored for 30 d before feeding. The bunkered wet distillers grains plus solubles material was mixed at feed delivery with an additional 29% cornstalks (DM basis) to attain the 41:59 by-product to cornstalks ratio. The distillers solubles mixture was fed directly from the bunker. Limestone was added to both by-product diets to achieve a minimum Ca:P ratio of 1.5:1. Salt and trace mineral blocks were offered free choice in the bunks for all treatments. Prior to trial initiation and at conclusion, cows were limit fed (1.9% of BW) a diet (40% brome hay, 10% alfalfa hay, and 50% wet corn-gluten feed; DM basis) for 5 d to minimize variation due to rumen fill. Two-day consecutive initial and final BW measurements were recorded to determine cow performance. Orts were recorded twice weekly to determine intake. Body condition score (Wagner et al., 1988) was assessed at the beginning and the end of the trial independently by 2 trained technicians. Ether extract content was determined using the method of the AOAC (1999). It was determined in our laboratory that the more traditional Soxlet procedure overestimated lipid values in distillers solubles and wet distillers grains plus solubles, so a gravimetric fat procedure was developed to more accurately measure fat content in these feeds (Bremer et al., 2010). In this procedure, fat is determined by incubating samples in a 1:1 hexane:diethyl ether solution for 9 h. Following incubation, a dilute

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hydrochloric acid solution is added to the samples before centrifugation. After centrifugation, the solvent layer remaining above the sample is removed and evaporated. Subsequently, the lipid from the sample remains after evaporation for determination of fat content. By-product samples were sent to a commercial laboratory for sulfur analysis (AOAC, 1999; method 968.08; Ward Laboratories, Kearney, NE). Performance data were analyzed using the MIXED procedures of SAS (SAS Institute Inc., Cary, NC) as a completely randomized design with pen as the experimental unit. A protected F-test (P < 0.10) was used to determine variation due to treatment, and means separation was conducted using a Bonferroni t-test.

RESULTS AND DISCUSSION Performance differences were observed for cows limit fed WDGS, DS, and CON diets (Table 2). Initial (5.7 ± 0.08) and final (6.0 ± 0.11) BCS were not different (P > 0.05) among treatments. Initial BW across treatments was similar (P = 0.20). Final BW was greater (P < 0.01) for cows fed WDGS (626 ± 7.0 kg) than for DS (612 ± 7.0 kg) and CON (611 ±

7.0 kg) cows. As designed, DMI was greater (P < 0.001; 10.4 kg) for CON cows compared with cows assigned to WDGS and DS treatments (7.7 kg; Table 1). Average daily gain tended (P = 0.09) to be numerically greater for the WDGS treatment (0.37 ± 0.20 kg/d) compared with the CON treatment (0.20 ± 0.20 kg/d). Average daily gain for the DS (0.31 ± 0.20 kg/d) treatment was intermediate to the WDGS and CON treatments. In addition, BW change tended (P = 0.09) to be numerically greater for the WDGS group (28.9 kg) compared with the CON group (15.4 kg). The CON performance results were likely due to lower DMI (1.8% of BW) than predicted by the NRC (1996) model. Cows in the CON treatment visually sorted their diet, which may have resulted in decreased total kilograms of energy consumed compared with the pretreatment calculated estimates. Cows fed the WDGS and DS treatments did not sort their diets and consumed essentially 100% of their diets daily. Corn-oil supplementation decreased NDF digestibility by 6 and 12% when included in the diet at 0.75 g/kg of BW and 1.5 g/kg of BW, respectively (Pavan et al., 2007). In the current study, dietary fat percentage, deter-

Table 2. Performance of cows limit fed a diet of wet distillers grains plus solubles or distillers solubles stored with cornstalks before feeding or full fed a forage control diet Item

WDGS1

DS2

CON3

SEM

P-value

Initial BW, kg Final BW, kg Initial BCS4 Final BCS4 BW change, kg ADG, kg/d DMI, kg

597 626 5.7 6.0 28.9 0.37 7.7

588 612 5.8 6.0 23.8 0.31 7.7

595 611 5.7 5.9 15.4 0.20 10.4

10 7 0.08 0.11 5.0 0.20 0.2

0.20 0.01 0.48 0.48 0.09 0.09 0.001

WDGS = cows limit fed (7.7 kg of DM daily) a diet of 41% wet distillers grains plus solubles with 59% cornstalks (DM basis). 2 DS = cows limit fed (7.7 kg of DM daily) a diet of 41% distillers solubles with 59% cornstalks (DM basis). 3 CON = cows fed ad libitum (10.4 kg of DM daily) a diet of 43% bromegrass hay, 34% cornstalks, and 23% alfalfa haylage (DM basis). 4 BCS on a scale of 1 (emaciated) to 9 (obese). 1

mined by ether extract procedure, was 9.2 and 4.9% for the DS and WDGS treatments, respectively (Table 3). As fat level in the diet increased, we hypothesized ADG would be negatively affected. Thus, a difference in ADG between DS and WDGS treatments was anticipated due to differences in NDF digestibility. In a study conducted by Corrigan et al. (2009), steers consumed a high-fiber diet and were supplemented with DDGS containing either 6.9 or 13.3% fat (DM basis). Intake and digestibility of both DM and OM were not statistically different between steers fed the 2 types of DDGS. However, NDF intake was reduced and digestibility tended (P = 0.14) to be lower (62.6 vs. 59.6%, for the low- and high-fat DDGS treatments, respectively). In the latter study, the calculated fat levels were determined using ether extract values. A biphasic feed lipid extraction procedure has been developed at the University of Nebraska–Lincoln (Bremer et al., 2010). Using this new procedure, calculated fat values were 4.1 and 5.5% for WDGS and DS, respectively (Table 3). Thus, our anticipated performance differences due to dietary fat, as determined by the NRC model (NRC, 1996), were not observed and likely resulted in the lack of negative response observed for ADG. Dietary sulfur level was 0.24 and 0.37% (DM basis) for the WDGS and DS treatments, respectively (Table 3). The maximum tolerable level for sulfur in forage-based diets is 0.40% (DM), as indicated by NRC (2005) guidelines. In addition, a portion of sulfur in by-products comes from methionine, a sulfur-containing amino acid prevalent in corn. Dietary protein supplied from wet distillers grains plus solubles is 30% degradable (Klopfenstein et al., 2008). Thus, 70% of sulfur contained in methionine is not degraded in the rumen. Although dietary protein supplied from distillers solubles is only 20% undegradable (Klopfenstein et al., 2008), symptoms of sulfur toxicity were not observed in the current study. Schoonmaker et al. (2003) concluded that limit-fed corn diets can

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Limit feeding beef cows ethanol by-products

Table 3. Dietary fat and sulfur content of treatment diets Item Sulfur, % (DM basis) Fat,4 % (DM basis) Fat,5 % (DM basis)

WDGS1

DS2

CON3

0.24 4.9 4.1

0.37 9.2 5.5

0.19 2.2 —

WDGS = cows limit fed (7.7 kg of DM daily) a diet of 41% wet distillers grains plus solubles with 59% cornstalks (DM basis). 2 DS = cows limit fed (7.7 kg of DM daily) a diet of 41% distillers solubles with 59% cornstalks (DM basis). 3 CON = cows fed ad libitum (10.4 kg of DM daily) a diet of 43% bromegrass hay, 34% cornstalks, and 23% alfalfa haylage (DM basis). 4 By-product samples analyzed by ether extract method. 5 By-product samples analyzed by modified biphasic lipid extraction. 1

be successfully used to maintain cows in mid- to late gestation and early lactation. In 2 studies, the authors compared stockpiled forage versus limit-fed corn as alternatives to hay for gestating and lactating beef cows. In the first experiment, cow BW postpartum was greatest for limit-fed cows and lowest for cows grazing stockpiled forage. Cows offered ad libitum access to hay were intermediate in BW and did not statistically differ from limitfed or grazed cows. No differences were observed in calving date, calf birth weight, calf weaning weight, or reproductive performance. In the second experiment, postpartum cow BW was greatest for hay-fed cattle, with cows in the grazed treatment group being the lightest. Body condition score, calving date, calf birth weight, calf weaning weight, and conception rate were not statistically different. All 3 treatments proved to be suitable management systems to winter cows. A study conducted by Susin et al. (1995) tested the effects of limit feeding a high-grain diet on lactation performance and rebreeding in ewes. Lamb growth was unaffected by treatment. Blood glucose levels were higher for the high-concentrate diet. However, no differences were observed in ewe reproductive performance. Shike et al. (2009) evaluated the effects of limit feeding DDGS or corngluten feed to lactating beef cows on cow performance and reproduction. Although calf ADG tended (P = 0.06)

to be lower for cows fed DDGS, initial and final cow BW and final pregnancy rates were similar (P > 0.16) between treatment groups. Considerations for calf health and performance and reproductive performance of the cows need to be evaluated in future experiments. In a search of the literature, we found no data where cows were limit fed bunkered feed by-products from the ethanol industry. Our data suggest nongestating, nonlactating beef cows can be limit fed ethanol by-products bunkered with forage. Selection of feed resources for beef cow nutrition programs can be made based on economics of the feed resources available. With the increasing availability of ethanol by-products, producers can consider using wet distillers grains plus solubles and distillers solubles in limit-fed rations. However, dietary fat and sulfur content should be closely monitored because of plant-to-plant variation (Buckner et al., 2011) and possible effects on animal health, performance, and forage digestion. Ethanol by-products can be purchased and stored with low-quality forages for use at later periods of time. Adams et al. (2008) reviewed storing wet distillers grains plus solubles with low-quality forages. Six experiments were conducted using wet distillers grains plus solubles stored in a silo bag under pressure at 2,068 kpa (300 psi). The authors concluded that minimum amounts of dry feedstuffs

needed for storage of wet distillers grains plus solubles were 15% grass hay, 12.5% wheat straw, 22.5% alfalfa, 50% DDGS, and 60% wet corn gluten feed with the remaining percentage as wet distillers grains plus solubles (DM basis). Furthermore, the authors recommended levels of 30% cornstalks, 30% wheat straw, and 40% grass hay on a DM basis with the remainder being wet distillers grains plus solubles for storage in bunker silos. The price of ethanol by-products is seasonal and mirrors feedlot inventories (Waterbury and Mark, 2008). Usually, there is a decrease in the price of wet distillers grains plus solubles and distillers solubles in late summer. This provides an opportunity for cow-calf producers to purchase by-products during times of low demand and store the product until it is needed at a later time.

IMPLICATIONS Diets of either WDGS or DS stored in a bunker with ground cornstalks can be successfully limit fed to nonlactating, nongestating beef cows in a drylot. Limit feeding a mixture of wet distillers grains plus solubles and cornstalks tended to improve ADG compared with feeding an ad libitum control diet. Limit feeding diets of either by-product stored in a bunker with ground cornstalks to mature cows does not negatively affect performance compared with forage feeding systems.

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